This invention relates to a chuck device for a dental handpiece.
In the prior art, there are known a variety of chucking devices for a dental handpiece, such as that shown in West German Patent No. 3048061. The chucking device shown in this West German Patent includes a dental bur for dental treatment having a peripheral groove formed in the vicinity of the proximal part thereof, and a head housing sleeve which is provided with a portion engaging with the peripheral groove and which is fitted in the head housing of the dental handpiece. The head housing sleeve may be turned about the longitudinal axis of the handpiece to establish or release the engagement between the peripheral sleeve and the engaging portion to effect connection or detachment of the dental bur. However, this type of the chuck device is not fully satisfactory in making quick exchange of the dental bur since it is necessary to turn the head housing sleeve before proceeding to exchanging the dental bur.
As another type of the chuck device for a dental handpiece, there is known a chuck device wherein the upper end of a sleeve adapted for accommodating and attaching the dental bur is formed with a slit in which a plate spring engaging with the dental bur is mounted, and wherein the arrangement is so made that a cam surface of a push button abuts on the plate spring at the time of exchanging the dental bur to release the engagement between the dental bur and the plate spring. However, with this type of the chuck device, since a groove is formed in the sleeve wall to secure the plate spring to the sleeve for accommodating and attaching the plate spring within the groove, limitations are necessarily imposed on the size of the plate spring and hence that of the engaging surface with the dental bur, so that it is not always possible to provide positive holding and attachment with the dental bur.